


If I Grow Old, Well I Know I'm Gonna Be, I'm Gonna Be The Man Who's Growing Old With You

by revenblue



Series: [collection] but you keep spinning 'round me just the same (Perryshmirtz) [74]
Category: Phineas and Ferb
Genre: Aftercare, Cloaca, Episode: s04e47 Act Your Age, Fingerfucking, Interspecies Sex, M/M, POV Second Person, Perry can talk because I say so, Rough Kissing, Rough Sex, Subspace, Tail Sex, Trans Male Character, Trust Kink
Language: English
Status: Completed
Published: 2019-05-23
Updated: 2019-05-23
Packaged: 2020-03-09 22:41:38
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,094
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18926431
Author URL: https://archiveofourown.org/users/revenblue/pseuds/revenblue
Summary: "Fightingyouwas a lot more fun than a mid-life crisis."It's an effort not to roll your eyes. Fighting youwashis mid-life crisis. Not that he's ever seemed to notice.





	If I Grow Old, Well I Know I'm Gonna Be, I'm Gonna Be The Man Who's Growing Old With You

Mid-life crisis, huh? Who does he think he's fooling?

As soon as you get back home, and it's _your_ home as much as his, now, you push the door firmly shut. Of all the harebrained schemes...

"I don't know why I _bothered_ ," he says, turning on his heel to face you, shoes clacking against the metal floor. "Fighting _you_ was a lot more fun than a mid-life crisis."

It's an effort not to roll your eyes. Fighting you _was_ his mid-life crisis. Not that he's ever seemed to notice.

Tapping his fingers against his side, he offers his other hand. "I kind of miss it, you know?" His voice is light as you take it, walking with him, like this is mere idle conversation. For him, it probably is. "The _scheming_ , the _fighting_ -"

Where's he going with this?

"You miss it too, don't you?" He glances at you as he says it, the corner of his mouth twitching up.

Of course you do. Who does he think you are? You're _Perry the Platypus_ , agent of the O.W.C.A., fighting is in your _blood_. And he's the only one who could ever match you: Heinz Doofenshmirtz, your _nemesis_.

You narrow your eyes, calculating angles and distances, and _leap_. Grabbing his shirt with fingers and hindclaws, you use your weight to slam him against the nearest wall, forcing the air out of his lungs. Just where you want him. You're breathless too, sucking in air, eyes glued to his parted lips, shaking with a familiar need.

The smell of his breath washes over you, an echo of his breakfast. Leftovers again, this time the meal he'd cooked for your date last night, and his ridiculously oversugared coffee. You'd criticise his choices, but you're just as bad.

Not that it matters, when it's never been easier to lean in and close the gap.

You don't, so _he_ does, capturing your mouth with his own. Firm pressure recedes to soft as his lips move lightly along your bill, lingering touches that send shivers through your fur. "You're holding back," he murmurs, breath hot against the sensitive skin, and you force back a whine. " _Kiss_ me, Perry the Platypus."

So you do.

Twisting your paws further into his shirt, you press him to the wall, kissing him with everything you've got. This is a fight, too. With your tongue, and not your fists, you battle him for dominance, growling in the back of your throat.

He huffs a laugh, tugging at your fur, one large hand coming up behind your head to hold you in place. A trap. Of course it is, this is your nemesis.

Another glare and you move a paw to his grey hair, pulling his head to one side so you can lick and nip at the bare skin there. Sink your teeth in to make him gasp. Leave a mark, _claim_ him as your own. He's _your_ nemesis, your lifelong enemy, your boyfriend, and you don't _share_.

"Are you _jealous_?" he says, digging his fingers into your tail until you're biting back a moan. "Is _that_ what this is?"

Yes. Yes it is.

You growl, sucking a dark bruise into his pale skin, over where the last one's nearly faded. Ten fucking years together and he still tries to _flirt_. He should know, by now, what you think about that.

Mouth pressed into your fur, he chuckles. "I _like_ this look for you, Perry the Possessivepus." He groans softly as you start on another bruise, the sound going straight to your cloaca. "You know I didn't _mean_ it, right?" Which tells you two things: Not only did he _know_ how you'd take it, the little shit did it _deliberately_.

Tugging at his hair, you drag his mouth back to yours, biting at his lip until it bleeds. The taste of copper fills your mouth, sharp and metal on your tongue.

"Yeah, you're fine." Twisting his long fingers into your fur, he smirks into your bill with every sound he wins from you, all the gasps and whines and moans you can't suppress any longer. "You love this, don't you."

Of course you do. These are the battles you live for, now. Not Good and Evil, but the two of you, still challenging each other after all this time.

Ten years hasn't dampened his spirit at all.

He kisses you again, tongue dancing together with yours; a salsa this time, or maybe a tango. Something with _passion_ , so close you're breathing the same air, hearts beating as one.

Breathless, you pull back just enough to gasp for air, eyes locked on his. You've always loved the deep blue of them: an ocean you yearn to get lost in, set adrift in the waves, diving below the surface to plumb the depths of him.

Sliding down the wall a little, he brushes his chapped lips over your bill again, the familiar shock of it racing down your spine and leaving your fur standing in its wake. He's murmuring something too, inaudible against the sound of your own heartbeat. Another tug at your tail and his hand moves too, finding its home between your legs, his broad human thumb tracing over your slick cloaca.

Trust him to make this about _sex_.

With a growl, you wrap your tail around his wrist, holding his hand in place while you rub yourself on it, panting in his ear. If it's sex he wants, it's sex he'll get. But _you're_ the one who's going to win this battle.

He presses another kiss to the underside of your bill, the corner of his mouth tugging up into a smirk. The hand in your fur slides down to the tip of your tail, then falls, only the echo of pressure to show he'd touched you at all. "You're _feisty_ today, huh?" he murmurs, over the unmistakable sound of him undoing his pants.

The familiar scent of his arousal fills the air around you, sharp on your tongue when you breathe. Sharp like his bony figure, his voice, his gaze. Everything about him designed for protection, to keep everyone at a distance. A cactus whose thorns hide a beauty beneath. 

To you, he _is_ beautiful. This ridiculous man you've spent the last ten years with, learning his every quirk and scar, watching his hair turn grey and the wrinkles on his face deepen as he grows old with you, holding his hand as your lives have changed around you, _this man_ has singlehandedly defined your idea of beauty.

The years have taken nothing of his attractiveness. If anything, he's only gotten better with age. He's still as uniquely _Heinz_ as the first time you'd seen him: still the same man you love, have always loved, _will_ always love.

And you _do_ love him. You can't not love the uneven twist of his lips in a grin, the same one that always accompanied his monologues; the deft hands, capable of so many things, expertly teasing at your cloaca; the shine of joy in his eyes as he carefully works a fingertip into you. The fucking _scheme_ to get you worked up like this in the first place. Jerk.

All you can do is kiss him again.

Moaning, he slips further down the wall, audibly fucking himself on his own fingers. Slick wet noises fill both the air and your thoughts, and for a moment you consider pausing to retrieve your _toys_. Then he shudders underneath your paws and you can't tear yourself away.

Instead, you let your tail fall, curling it around the other wrist to guide his hand. Harder, first. Shove his fingers inside, again and again, make him submit to your claim on his body and on his pleasure. Then you pull back and-

"Perry the Platypus," he groans into your bill, as you brush his fingers over his clit, light enough that he's straining for contact. "Fuck. I need-"

You. He needs _you_.

Releasing his wrist, you push your tail through his slickness directly, not caring about the mess it'll make of your fur. It's worth it to take him apart like this. You rub at his clit with a firm pressure, swallowing his gasps and moans as he clutches at your backfur, sinking down on his finger inside you: _taking_ him in every sense of the word.

He's putty in your paws, warm and pliant as you tip his head back to lick up the line of his throat, over the slight lump you know he wishes was more prominent. How often has he mentioned it over the last decade? Not that you've ever felt anything was lacking in him for it.

You huff a laugh, right over his damp skin. It's a ridiculous idea, really. The only things he _lacks_ are common sense and the concept of self-preservation.

If you have to save him from his own mistakes _one more time_...

...you'd do it.

That's part of the commitment you made, all those years ago. Before he asked you to marry him. Before you asked him to join you. Before everything, when all you were to each other was a nemesis, you made a promise.

He shudders, hand sliding up your spine to the scruff of your neck. "I'm so close, Perry the Platypus, _please_ -"

Growling in the back of your throat, you claim his mouth in another rough kiss, fucking him with tongue and tail until he clutches tight at your shoulders, shaking with orgasm. Another shudder and his knees buckle, dropping you both to the floor.

The impact forces his finger into your cloaca whole, pushing the air from your lungs. Knuckle at your fur, he pins you to his chest with his other hand while his breathing calms, long enough that you're clutching at the shirt he's still wearing, silently begging your muscles to obey when they _won't_.

"I've got you," he murmurs into your fur. He's solid under you, heartbeat thrumming through your bill, holding you close. A scritch of his fingers and you melt into him with a chirr, unable to stop yourself. It's been ten years, for fuck's sake, how are you still so helpless to resist him?

Pressing his lips to your sensitive bill, he finally rocks his finger into you, a gentle back and forth that leaves you growling in halfhearted protest. "Re _lax_ , Perry the Platypus," he says, in that tone he gets when he's rolling his eyes. Why wouldn't he? It's not like it's your _safeword_. "You're always so _tense_ , you know that? I mean of course you are, how long have I known you? But you're _extra_ tense today. Has your _agency_ been overworking you again? Don't answer that, I can _tell_."

All you can do is tremble, eyes squeezed shut, completely at his mercy. Again. Not that you're upset, as such. You both know you'd be putting up more of a fight if you didn't want this, if you didn't trust him unconditionally, and he takes that as permission to guide your mouth back to his in another kiss.

The touch of his lips sends a ripple down your spine, his whole body alight with nerves before you. You can trace every beat of his heart, every twitch of his muscles, and even his arms, so different but no less a part of him.

He pulls back, just far enough that his breath is the only contact you get, and grins. Wrapping his hand around your paws, he eases them free of his shirt.

"Come on, let me see you," he murmurs, lifting your arms over your head and pulling you into a stretch. "Yes, like that- oh, you're _gorgeous_ , Perry the Platypus. I know I say that every time, but _wow_."

Shifting back to sit upright against the wall, he rakes his eyes over your straining body, the heaving chest and exposed belly you wouldn't dare show anyone else. Only him. Only ever _him_. He's earned the right to see you like this, with tears in your eyes and every vulnerability on display, trusting him to take care of you.

You exhale, showing him your bare throat too, head tipped up so your bill brushes his hand. Rough lips press to the underside of your bill, dragging down along your neck, and you shiver, cloaca tightening around his finger.

Fuck, you love it when he does this.

Leaning in, he puts his face to the side of your head, breath warm in your ear. "Ready for more?" he murmurs, curling the finger buried deep inside you.

"Yes," you groan, grinding your hips into his hand. The language still feels foreign in your mouth, clumsy and awkward, even after all the time he's spent teaching you over the last few years, but it's worth it to hear him suck in a breath. "Heinz-"

He kisses his name off your bill, a second finger at your cloaca and pushing in before you can so much as breathe. Hips twitching under you like he's trying to fuck you with one of _his_ toys, he claims you inside and out, top and bottom, spreading you open around his fingers while his tongue dances with yours: a waltz this time, slow and lingering.

"Perry the Platypus," he whispers when he comes back up for air, pupils blown, the blue of his eyes barely a sliver around the edge. "Talk to me, tell me what you need, I want to hear you." Swallowing, he curls his fingers inside you, one after another. " _Say my name_."

Tears pour down your cheeks as you choke out the words. "Heinz, fuck, _please_ -"

" _Language_ ," he breathes, the fucking hypocrite, with a hint of a smile in his voice. His hand tightens around your paws, holding you far enough back that you can't quite reach his mouth for the contact you so desperately crave. "Do you kiss your _mother_ with that mouth?"

Somewhere in the midst of your scrambled thoughts you pull together enough coherence to roll your eyes. "Kiss _you_ , don't I?" Oh yes, _this_ is a thought you can focus on. "Lips-" You can't get enough of the taste of them, the taste of _him_. "-neck-" The pale skin's already bruising where you marked him. Fuck, you love this man. Aiming a fuck-drunk grin at him, you slide your tail between and behind his legs, teasing at his... "- _ass_."

He squeaks, flushing that warm human pink he looks so good in, fingers stilling where they're stuffed deep inside you. "That's _different_ , Perry the Platypus! You can't just-"

" _Heinz_." You can't help the smirk as he reels back from the _weight_ of it, your whisper quelling his indignant squawks. His name's on your tongue where it belongs, his breath's mingling with yours, his neck's purple with your claim. He's _yours_. Time to remind him of that. " _Kiss_ me, Heinz Doofenshmirtz."

And he does.

Dropping your paws, he grabs your head roughly and crashes your mouths together with renewed urgency, fingertips digging into your skull. "Gonna _fuck_ you," he groans into your bill, dragging his other hand back from your cloaca, "so _hard_ -" His fingers slam back in to punctuate the word. "-you won't walk straight for a _week_. How's that sound?"

You cling weakly to his shirt, tears flowing from your eyes again. Ten years, ten _fucking_ years, and the thought of ceding control to him still makes your stomach drop. Fuck, you want to so much, but you can't bring yourself to take that last step.

"Shh, it's okay." His voice softens as he slows his thrusts, stroking his other hand down your spine. "I've got you," he murmurs, kissing the top of your bill... 

...and you let go.

Time loses its meaning as you let yourself melt into his touch, tension bleeding from your muscles. You trust him. Of course you trust him, Heinz, your nemesis. The world narrows down to his fingers in your cloaca, his hand on your back, his lips on your bill, the human _warmth_ of him under you, as you give your whole self to the man you love.

He murmurs something indistinct, palm sliding up through your fur to take your fedora. Settling his hand in its place, he kisses you again, fingers curling inside you until you're shaking with it.

_Heinz_ , you think, his name the only thing that makes sense to your addled mind. _Heinz, Heinz, Heinz_.

Awareness returns slowly, rising up like the sand under your hindpaws as you're washed ashore. He's still holding you, both arms curled loosely around your aching body, voice rising and falling in a steady rhythm.

Of course he's rambling, you muse fondly, the corners of your bill twitching up: this is _Heinz_. He can't exist in a space without doing something to fill it somehow, whether it's a monologue in the silence, or fingers or tongue or _toys_ in your cloaca. Or his very self, nestled comfortably in your heart where he's been for the last decade, in a hole you hadn't known was empty until he'd filled it.

"-oh, you're back? You're back. Don't think I don't notice that _smile_ , Perry the Platypus, I know you love this-"

You snort, shaking your head. "Love _you_."

Letting out an amused huff, he presses a soft kiss to your brow. "Yes, I love you too, now drink up." He nudges a straw against your bill until you take it, sipping at the iced tea. " _That's_ better. I may be fresh off a mid-life crisis, but I've still got to hurt you the _right_ way, with cartoonish traps and all those _toys_ I purchased off the internet. And safewords. That part's not negotiable, so don't even _try_. I'm not that kind of guy, you know?"

"'f course," you mumble around the straw. You wouldn't have given him two-thirds of your life if he was. Dragging yourself along his warm body, you make yourself comfortable, bill tucked under his chin. "Love you."

"Not even when I was _Evil_ ," he continues, working himself up to full monologue while his fingers comb through your fur. "I had _standards_ , Perry the Platypus. So many evil scientists don't have _finesse_ , or _pizzazz_ , but I had it _good_. Not literally Good, that came later, but... you know what I mean. It was fulfilling, like I was always _meant_ to be an Evil scientist, planning _schemes_ and _monologues_ and _traps_... Then I met _you_ , and... and that was my mid-life crisis, was't it."

All you can do is roll your eyes, because yes. Yes it was.

**Author's Note:**

> Title from [I'm Gonna Be (500 Miles)](https://www.youtube.com/watch?v=tbNlMtqrYS0) by the Proclaimers.
> 
> [Perryshmirtz Discord server](https://discord.gg/eEhRMq3)


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